Asyncpg crashes if $HOME is not readable and no password is supplied

[Drakekin]

• asyncpg version: 3.4.1
• PostgreSQL version: 10.5
• Python version: 3.6
• Platform: Ubuntu 16.04
• Do you use pgbouncer?: no
• Did you install asyncpg with pip?: yes
• Can the issue be reproduced under both asyncio and
  uvloop?: not relevant

When running asyncpg to connect to postgresql without a password (such as using certificate or peer auth) where the home directory as given in $HOME is not readable by the executing system user, asyncpg crashes as it cannot read $HOME/.pgpass as opposed to the expected behaviour that asyncpg should ignore the error and continue to connect.

[elprans]

#357 should fix this. Before that is released, you can work this around by passing a path with a readable parent directory in the passfile connection argument. The path doesn't have to exist.